adnanoner

    /**
     * Perform an "Upsert" using the "INSERT ... ON CONFLICT ... " syntax in PostgreSQL 9.5
     * @link http://www.postgresql.org/docs/9.5/static/sql-insert.html
     * @author https://github.com/adnanoner
     * inspired by: https://gist.github.com/plurch/118721c2216f77640232
     * @param {string} tableName - The name of the database table
     * @param {string} conflictTarget - The column in the table which has a unique index constraint
     * @param {Object} itemData - a hash of properties to be inserted/updated into the row
     * @returns {Promise} - A Promise which resolves to the inserted/updated row
     */